• 전기화학회지
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• 제5권2호
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• pp.62-67
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• 2002

용융탄산염 연료전지의 성능 저하와 수명 감소의 원인이 되는 부식 현상을 규명하고자 분리판 재료로 가장 널리 사용되고 있는 AISI-type 316L stainless steel을 대상으로 62Li/38K계 용융탄산염 내에서의 부식 실험을 수행하였다. 부식의 형태 및 속도는 환경에 의하여 다양하게 변화하게 되며, 용융탄산염 내에서 AISI-type 316L stainless steel의 부식 속도는 부식 반응에 의하여 형성되는 부동태 산화막의 안정성에 의하여 크게 영향을 받는다. 전기화학적 분극 거동을 분석한 결과 용융탄산염 연료전지의 anode가슨 분위기에서는 안정한 부동태 산화막이 형성되지 않았다. 순환 전압전류법과 정전위법을 이용한 부식 생성물의 X-ray분석을 통하여 특정한 전기화학적 전위 영역에서 반응기구와의 인과관계를 규명하고 다양한 형태의 부식 반응들을 분리해 내었다.

• 대한금속재료학회지
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• 제49권7호
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• pp.515-521
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• 2011

Small punch creep testing has received attention due to the convenience of using smaller specimens than those of conventional uniaxial creep tests, which enables creep testing on developing or currently operational components. However, precedent studies have shown that it is necessary to consider friction between the punch and specimen when computing uniaxial equivalent stress from a finite element model. In this study, small punch creep behaviors of AISI 316L stainless steel, which is widely used in high temperature-high pressure machineries, have been compared for the two different ceramic balls such as $Si_3N_4$ and $Al_2O_3$. The optimal range of the friction coefficient is 0.4~0.5 at $650^{\circ}C$ for the best fit between experimental and simulation data of AISI 316 L stainless steel. The higher the friction coefficient, the longer the creep rupture time is. Therefore, the type of ceramic ball used must be specified for standardization of small punch creep testing.

• Journal of Advanced Marine Engineering and Technology
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• 제15권4호
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• pp.22-28
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• 1991

The crevice corrosion behavior on austenitic AISI 304 and 316L stainless steel welded by TIG, MIG, $CO_2$ and SMA was studied. The results are as follows : In 10% $FeCl_3$ solution and natural sea water sampled near Mokpo port, the base metal of 304 stainless steel showed small amount corrosion, whereas 316L stainless steel did not showed any corrosion in the test periods. The weight loss caused by crevice corrosion increased with increasing weld heat input and residual .delta. ferrite formed in welded part. The corrosion resistance of the welded part was in the order of TIG, MIG, $CO_2$ and SMA. From this tendency, it is proved that the smaller heat input gives the better corrosion resistance.

• 열처리공학회지
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• 제34권6호
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• pp.315-322
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• 2021

In this study, we investigate the variation in microstruture and mechanical property of austenitic 316L stainless steel during long-term material degradation. To simulate the material degradation, the AISI 316 steel was exposed to accelerate under a temperature of 600℃ for up to 10000 hours at each predetermined heat treatment time. As the long-term material degradation time increase, the grain shape was changed from polygonal grains with annealing twins to circular grains. Most twins distributed uniformly interior of grains are recovered and disappered with long-term material degradation. Also, the δ ferrite along grain boundaries decomposed and transformed into the σ phase resulting in decrease of elongation of austenitic 316L stainless steel.

• 한국표면공학회지
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• 제48권6호
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• pp.269-274
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• 2015

In this experiment, post-nitriding treatment was performed at $400^{\circ}C$ on AISI 316 stainless steel which was plasma carburized previously at $430^{\circ}C$ for 15 hours. Plasma nitriding was implemented on AISI 316 stainless steel at various gas compositions (25% $N_2$, 50% $N_2$ and 75% $N_2$) for 4 hours. Additionally, during post nitriding Ar gas was used with $H_2$ and $N_2$ to observe the improvement of surface properties. After treatment, the behavior of the hybrid layer was investigated by optical microscopy, X-ray diffraction, and micro-hardness testing. Potentiodynamic polarization test was also used to evaluate the corrosion resistance of the samples. Meanwhile, it was found that the surface hardness increased with increasing the nitrogen gas content. Also small percentage of Ar gas was introduced in the post nitriding process which improved the hardness of the hardened layer but reduced the corrosion resistance compared with the carburized sample. The experiment revealed that AISI 316L stainless steel showed better hardness and excellent corrosion resistance compared with the carburized sample, when 75% $N_2$ gas was used during the post nitriding treatment. Also addition of Ar gas during post nitriding treatment degraded the corrosion resistance of the sample compared with the carburized sample.

• 전기화학회지
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• 제27권1호
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• pp.8-14
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• 2024

오스테나이트계 스테인리스강은 내식성 및 성형성이 양호하여 다양한 분야에 적용되며, 구리계의 합금을 용가재로 하는 브레이징을 통하여 다양한 형상의 제품으로 가공되어 활용되고 있다. 이때, 구리 기반의 용가재와 스테인리스강의 계면에서 갈바닉 셀을 형성하여 부식을 촉진할 수 있으며, 확산을 통해 스테인리스강에 고용 시 형성되는 구리 과다 영역(Cu-rich region)은 공식 발생의 기점이 되어 내식성을 저하시킨다. 본 연구에서는 브레이징이 적용된 스테인리스강의 내식성을 개선하고자, AISI 316L 스테인리스강에 암모니아 가스를 이용한 질화처리를 적용하였다. 질화처리한 시편은 처리 온도가 증가함에 따라 두께가 증가하고 표면 경도가 높아졌다. 동전위분극시험을 통해 내식성을 평가한 결과 질화층 내 고용된 질소의 용출 및 부동태 거동으로 모재대비 내식성이 개선되었지만 처리온도가 높아 크롬질화물(CrN) 분율이 증가하는 경우 내식성이 감소하였다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 춘계학술발표회 논문집
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• pp.177-178
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• 2012

In this experiment, post-nitriding treatment has been performed at $400^{\circ}C$ on AISI 316 stainless steel which is plasma carburized previously at $430^{\circ}C$ for 15 hours. Plasma nitriding was implemented on AISI 316 stainless steel at various gas compositions (25% N2, 50% N2 and 75% N2) for 4 hours. Additionally, during post nitriding Ar gas was used with H2 and N2 to observe the improvement of treatment. After treatment, the behavior of the hybrid layer was investigated by optical microscopy, X-ray diffraction, and micro-hardness testing. Potentiodynamic polarization test was also used to evaluate the corrosion resistance of the samples. Meanwhile, it was found that the surface hardness increased with increasing the nitrogen gas content. Also small percentage of Ar gas was introduced in the post nitriding process which improved the hardness of the hardened layer but reduces the corrosion resistance compared with the carburized sample. The experiment revealed that AISI 316L stainless steel showed better hardness and excellent corrosion resistance compared with the carburized sample, when 75% N2 gas was used during the post nitriding treatment. Also addition of Ar gas during post nitriding treatment were degraded the corrosion resistance of the sample compared with the carburized sample.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1998년도 추계학술발표회요약집
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• pp.216-216
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• 1998

• 한국재료학회:학술대회논문집
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• 한국재료학회 1996년도 재료학회 추계학술발표회
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• pp.13-13
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• 1996

• 한국재료학회:학술대회논문집
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• 한국재료학회 1996년도 재료학회 춘계학술발표회
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• pp.97-97
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• 1996